Weather Agent

The Weather Agent provides weather data retrieved from Weather Underground to agents. It provides an example of accessing an external resource and publishing it to the VOLTTRON Message Bus. It also provides an example of dividing data up into topics and for implementing the “all” topic at each level. The Weather agent retrieves data in two ways.

Usage

In the first, the agent periodically retrieves information about a specific area from weather underground and publishes current information periodically (default once an hour) to the message bus. The area is set in the agents configuration file. Agents that are interested in this information can subscribe to “weather/<subtopic>/<field>” where <subtopic> and <field> are described in the topics section below. Agents may also subscribe to “weather/all” which will give them a hierarchical json document laid out according to the weather agent topics (as below) or “weather/<subtopic>/all” which provides a json document with all of the fields for the weather topic specified.

The second mode of operation is on demand. An agent may specifically request weather data for an area by posting a message on the “weather/request” topic. The agents message includes the identifying information about the area (region/city, or zip code) which is used in the request to Weather Underground. The Weather Agent replies on the “weather/response” topic (to avoid confusion with agents subscribing to the periodic posts). As with the first mode of operation, the agent making the request can subscribe to the “weather/response/all” subtopic, “weather/response/<subtopic>/all”, or “weather/response/<subtopic>/<field>” topics to receive the response data from the Weather Agent. Agents making requests must have the requesterID header set.

3.0 Agent Example

To make a request of the weather agent.

Python 2.7.6 (default, Jun 22 2015, 17:58:13)
[GCC 4.8.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from volttron.platform.vip.agent import *
>>> a = Agent()
>>> import gevent
>>> gevent.spawn(a.core.run).join(0)
>>> a.vip.pubsub.publish('pubsub', 'weather/request', headers={'requesterID': 'agentid'}, message={'zipcode': '99336'}).get(timeout=10)

headers = {}
headers[headers_mod.REQUESTER_ID] = agent_id
msg = {"zipcode": "99352"}
self.publish_json('weather/request', headers, msg)

Make sure you get your own API Key from Weather Underground before using the weather agent.

Sample Output

Following is the response message that would be returned on “weather/all” or “weather/response/all”.

{
    "cloud_cover": {
        "UV": "6",
        "solarradiation": "",
        "visibility_km": "16.1",
        "visibility_mi": "10.0",
        "weather": "Clear"
    },
    "location": {
        "display_location": {
            "city": "Richland",
            "country": "US",
            "country_iso3166": "US",
            "elevation": "121.00000000",
            "full": "Richland, WA",
            "latitude": "46.28490067",
            "longitude": "-119.29721832",
            "state": "WA",
            "state_name": "Washington",
            "zip": "99352"
        },
        "local_tz_long": "America/Los_Angeles",
        "observation_location": {
            "city": "Richland, Richland",
            "country": "US",
            "country_iso3166": "US",
            "elevation": "397 ft",
            "full": "Richland, Richland, Washington",
            "latitude": "46.285866",
            "longitude": "-119.304375",
            "state": "Washington"
        },
        "station_id": "KWARICHL21"
    },
    "precipitation": {
        "dewpoint_c": 7,
        "dewpoint_f": 44,
        "dewpoint_string": "44 F (7 C)",
        "precip_1hr_in": "0.00",
        "precip_1hr_metric": " 0",
        "precip_1hr_string": "0.00 in ( 0 mm)",
        "precip_today_in": "0.00",
        "precip_today_metric": "0",
        "precip_today_string": "0.00 in (0 mm)"
    },
    "pressure_humidity": {
        "pressure_mb": "1014",
        "pressure_trend": "-",
        "relative_humidity": "40%"
    },
    "temperature": {
        "feelslike_c": "20.6",
        "feelslike_f": "69.1",
        "feelslike_string": "69.1 F (20.6 C)",
        "heat_index_c": "NA",
        "heat_index_f": "NA",
        "heat_index_string": "NA",
        "temp_c": 20.6,
        "temp_f": 69.1,
        "temperature_string": "69.1 F (20.6 C)",
        "windchill_c": "NA",
        "windchill_f": "NA",
        "windchill_string": "NA"
    },
    "time": {
        "local_epoch": "1368724778",
        "local_time_rfc822": "Thu, 16 May 2013 10:19:38 -0700",
        "local_tz_offset": "-0700",
        "local_tz_short": "PDT",
        "observation_epoch": "1368724692",
        "observation_time": "Last Updated on May 16, 10:18 AM PDT",
        "observation_time_rfc822": "Thu, 16 May 2013 10:18:12 -0700"
    },
    "wind": {
        "pressure_in": "29.94",
        "wind_degrees": 3,
        "wind_dir": "North",
        "wind_gust_kph": "4.8",
        "wind_gust_mph": "3.0",
        "wind_kph": 2.7,
        "wind_mph": 1.7,
        "wind_string": "From the North at 1.7 MPH Gusting to 3.0 MPH"
    }
}

For a more comprehensive listing of Weather Agent subtopics see WeatherAgentTopics